1. Field of the Invention
The present invention relates to the field of back lighted displays in general. In particular, the present invention relates specifically to a simple, efficient backlit display structure with multiple LED's arranged to transmit light into a light guide plate configured to uniformly illuminate the back of a readily replaceable translucent image sheet. The display may be incorporated with a decorative frame which also may be illuminated by the same or different LED's. The display may also be incorporated in table top boxes for condiments, straws, napkins or other conveniences for restaurant customers where it is useful for displaying advertising or current menu features. Another version has a light guide which does not provide uniform back lighting but only illuminates temporary marks from a marker or crayon on the front surface of the light guide, the background remaining dark.
2. Description of the Known Art
Advertising display devices and backlighting devices for general purposes have been known as shown in the following patents: U.S. Pat. No. 3,106,314, issued to Spears, on Oct. 8, 1963; U.S. Pat. No. 4,714,983, issued to Lang, on Dec. 22, 1987; U.S. Pat. No. 5,377,084, issued to Kojima et al., on Dec. 27, 1994; U.S. Pat. No. 5,730,518, issued to Kashima et al., on Mar. 24, 1998; U.S. Pat. No. 5,842,297, issued to Tung, on Dec. 1, 1998; U.S. Pat. No. 6,367,392, issued to Moore, on Apr. 9, 2002; U.S. Pat. No. 6,447,136, issued to Liu et al., on Sep. 10, 2002; U.S. Pat. No. 6,530,164, issued to Gai, on Mar. 11, 2003; U.S. Pat. No. 6,539,656, issued to Maas et al., on Apr. 1, 2003; U.S. Pat. No. 6,561,672, issued to Lessard, on May 13, 2003; U.S. Pat. No. 6,691,443, issued to Slayden, on Feb. 17, 2004; U.S. Pat. No. 6,926,420, issued to Sung, on Aug. 9, 2005; U.S. Pat. No. 6,968,959, issued to Garvin, on Nov. 29, 2005; U.S. Pat. No. 7,024,809, issued to Poma, on Apr. 11, 2006; U.S. Pat. No. 7,026,916, issued to Alexander, on Apr. 11, 2006; U.S. Pat. No. 7,048,398, issued to Bahramian, on May 23, 2006; U.S. Pat. No. 7,063,449, issued to Ward, on Jun. 20, 2006; U.S. Pat. No. 7,131,764, issued to Hsu et al., on Nov. 7, 2006; U.S. Pat. No. 7,186,015, issued to Kimmet et al., on Mar. 6, 2007; and U.S. Pat. No. 7,226,200, issued to Tsai, on Jun. 5, 2007.
The information deemed most relevant in these patents is as follows:
U.S. Pat. No. 6,447,136 issued to Liu et al. on Sep. 10, 2002 discloses a liquid crystal display having a light guide plate for a back light system. This patent discusses light guide plates with surface irregularities in the form of annular protrusions.
U.S. Pat. No. 7,131,764 issued to Hsu et al. on Nov. 7, 2006 discloses a backlight apparatus with and edge lit guide element with concavities for directing light. FIG. 4c discloses a hexagon configuration.
U.S. Pat. No. 5,377,084 issued to Kojima et al. on Dec. 27, 1994 discloses a surface illuminating apparatus including a light guide plate, irregularly reflecting plate and back reflecting plate having incandescent light sources at each lateral end. FIGS. 7, 8 and the background discuss relevant areas of this art.
U.S. Pat. No. 6,926,420 issued to Sung on Aug. 9, 2005 discloses a backlight unit for a liquid crystal display having reflective plate with reflection dots with varying dot size and which cooperates with a smooth light guide plate.
Additional patents specifically directed to napkin holders are as follows:
U.S. Pat. No. 6,561,672 issued to Lessard on May 13, 2003 discloses an illuminated holder for finding miscellaneous objects in the dark. The illumination is on the sides of the unit and does not teach an backlit illuminated advertisement section.
U.S. Pat. No. 3,106,314 issued to Spears on Oct. 8, 1963 discloses an advertising napkin holder. The advertisement is insertable and removable from flanges on the sides of the unit, but no illuminated advertisement is provided.
The other patents disclose additional illumination and display elements of other forms.